AJP - Regulatory, Integrative and Comparative Physiology, Vol 263, Issue 1 34-R38, Copyright © 1992 by American Physiological Society
Adrenergic regulation of neonatal brown fat adenylyl cyclase and Gs alpha activity
A. Chaudhry and J. G. Granneman
Department of Psychiatry, Wayne State University School of Medicine, Detroit, Michigan 48235.
Norepinephrine (NE)-stimulated adenylyl cyclase (AC) activity increases
during the perinatal period in rat brown adipose tissue (BAT), and this
increase is associated with changes in the activities of both the catalytic
subunit (C) and Gs alpha, the GTP-binding protein that mediates activation
of C. The present study examined the role of the sympathetic nervous system
in the postnatal sensitization of AC. The sympathetic innervation of BAT
increased 7- to 13-fold after birth, and this increase was temporally
correlated with the postnatal enhancement of AC responsiveness.
6-hydroxydopamine (6-HDA) treatment of neonates reduced tyrosine
hydroxylase levels by greater than 90%. This treatment greatly reduced the
perinatal increase in NE- and NaF-stimulated AC and completely abolished
the increase in forskolin-Mn(2+)-stimulated activity. However,
sympathectomy did not alter the postnatal increase in Gs alpha-specific
activity and did not prevent the postnatal reduction in Gs alpha levels.
These results demonstrate that the sympathetic innervation of BAT develops
fully after birth and is essential for the postnatal increase in the
activity of C but not of Gs alpha.
